1. Field of the Invention
Embodiments herein relate to methods and devices for connecting adjacent blood vessels, e.g., an artery and an adjacent vein, to adapt the vein for arterial blood flow, and more particularly, embodiments relate to devices such as differential dilation stents for creating and maintaining a pathway between an artery and a vein to form a fistula connecting the blood vessels.
The superficial femoral arteries and the popliteal arteries are leg arteries that provide blood flow through the legs and to the feet, particularly to the skin and areas just below the skin. Patients suffering from partial or complete occlusions in such arteries typically experience claudication (e.g., leg pain or limping while walking) and difficulty in healing wounds on the legs due to ischemia, although the deep femoral artery may provide enough circulation that at least the pain is reduced by resting. However, standard open bypass often is impossible on such patients, particularly those with diabetes-narrowed arteries, because of the substandard ability to heal the necessary incisions. Neither performing angioplasty nor inserting stents is likely to help where the vessels are too small or the occlusion extends all the way down to the foot. In severe cases, non-healing ulcers or resting pain may leave no alternative except amputation. Thus, peripheral vascular disease presents a serious health risk.
2. Description of the Background Art
Commonly assigned and invented U.S. Pat. No. 7,300,459 describes a stent with a covering that can be differentially dilated.